WASHINGTON (CNN) -- Aides to Attorney General Alberto Gonzales on Tuesday rejected published assertions that Gonzales misled a congressional committee when he testified more than two years ago that he was unaware of FBI wrongdoing in terrorism investigations.

Alberto Gonzales testifies before the Senate Judiciary Committee in April.

However, in a conference call with reporters late Tuesday, the officials had no information on whether Gonzales, who was listed in the documents as a recipient, had seen any of the internal FBI reports of potential legal violations by FBI agents before he appeared before Congress on April 26, 2005.

"I don't have that," said Gonzales chief spokesman Brian Roehrkasse.

James Baker, counsel for intelligence policy at the Justice Department's National Security Division, said he did not recall discussing with Gonzales the specific cases referred to in the reports, but said he had "discussed and informed attorneys general, including this one, about mistakes the FBI has made."

The newly released documents obtained by the Electronic Frontier Foundation under a Freedom of Information Act lawsuit were first reported by the Washington Post.

The heavily redacted documents show an FBI official sent a report dated April 21, 2005, to the Intelligence Oversight Board (IOB), a copy of which was also sent to Gonzales. Six days later Gonzales testified at a Senate Intelligence Committee hearing that "there has not been one verified case of civil liberties abuse."

The IOB is a government body that receives reports from intelligence agencies about possible violations of executive orders and powers.

Democrats seized on the published report.

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"The reports today that the attorney general misled Congress regarding violations of Americans' privacy and civil liberties by his department are deeply disturbing and warrant further inquiry," said Senate Judiciary Committee Chairman Patrick Leahy, D-Vermont. Leahy promised to press Gonzales on the issue when Gonzales testifies later this month.

The violations of regulations and statutes involve the FBI's use and reporting of national security letters, which compel third parties to secretly disclose personal information on suspects in terrorism investigations. The letters, which do not require court approval, were a controversial authority included in the Patriot Act, which was up for renewal when Gonzales testified there were no abuses.

Assistant Attorney General Kenneth Wainstein stressed the reports of potential violations do not necessarily reflect civil liberties abuses. He said an important distinction must be made between abuses and mistakes.

"When intelligence investigations are done at the pace and the rapidity and the urgency that they're done now after 9/11, there are the possibilities of mistakes," Wainstein said.

The developments Tuesday came as the FBI was in the process of implementing major revisions in its procedures on how agents must document and carry out their use of national security letters. A recent inspector general report found hundreds of cases in which agents had improperly conducted and reported national security letter investigations of potential terrorism suspects, and prompted the FBI changes.

FBI Director Robert Mueller accepted blame for the errors, and developed new rules, which he shared Monday with civil liberties groups.

Several of the groups said they would continue to push for legislation to take away the power of the FBI to issue the national security letters without court approval, and they questioned the FBI's ability to police itself.E-mail to a friend